Convergent syntheses are more efficient than linear syntheses because you risk less if one branch of your synthesis fails and because the same number...
Convergent syntheses are more efficient than linear syntheses because you risk less if one branch of yoursynthesis fails and because the same number of steps in a linear synthesis give a lower overall yield. Forinstance, in our synthesis we had three branches that converge to hexaphenylbenzene. We ran eight reactions. Ifthe yield of each reaction was 90 %, then our overall yield would be between 72 and 66 %, depending on whichbranch is limiting. (an the other hand, if we had to do eight consecutive 90 % yield reactions, the overall yieldwould be 43 % (0.9 x 100 %). Unfortunately it is not valid to calculate the overall yield on each branch of a convergent synthesis, only the overallyield of the branch of the limiting reagents. For instance if benzil and tetraphenylcyclopentadienone are thelimiting reagents in their respective reactions, then we can only report the overall yield from benzaldehyde viabenzoin. If dibenzyl ketone and tetraphenylcyclopentadienone are the limiting reagents then we can only reportthe overall yield from phenylacetic acid. And if diphenylacetylene is the limiting reagent then we could only reportthe overall yield from benzaldehyde (or benzyltriphenylphosphonium chloride if it is the limiting reagent) viastilbene. Use the following atomic weights to determine the limiting reagent branch of our synthesis. Then calculate themissing % yield(s) for that branch. Finally report the overall % yield from the starting reaction of that branch tohexaphenylbenzene. Give only 2 significant figures. If your final answer is a whole number, do not write adecimal. The grams next to an arrow are the grams of the compound previous to the arrow used in the reaction. The”grams made" are the grams of the product of that reaction. The % next to an arrow are the % yield of eachrespective reaction. This link also explains how to answer this question. C=12,H=1,0=16
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